<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<ul>
    <li>item-1</li>
    <li>item-2</li>
    <li>item-3</li>
    <li>item-4</li>
    <li>item-5</li>
    <li id="item6">item-6</li>
    <li>item-7</li>
    <li>item-8</li>
    <li>item-9</li>
</ul>

<script src="/vendor/jquery-1.12.4.js"></script>
<script>
    $(function () {
        var elements=$('li');
        console.log(elements.length)//获取jquery对象元素的数量
        console.log(elements.get[0]) //get([index])返回DOM元素或元素集合
        console.log(elements.eq(0))
        console.log($('li:eq(0)')) //eq(index)返回Jquery对象
        console.log(elements.first())
        console.log(elements.last())
        console.log(elements.toArray())//toArray:把jquery对象转化为DOM元素的一个数组
        console.log(elements.get())//不加参数的get和toArray功能类似


    })
</script>
</body>
</html>